Carburetor system



Jan. 15, 1952 R, MCDONNELL 2,582,389

CARBURETOR SYSTEM Filed Feb. 16, 1949 3 Sheets-Sheet 1 INVENTOR. Randall L .McDonn e11 Jan. 15, 1952 R. L. MwoNNELL 2,582,389

CARBURETOR SYSTEM Filed Feb. 16 1949 3 Sheets-Sheet 2 INVENTOR. Randall LMcDonnell m .n *ozmz,

Aflernegs Jan. 15, 1952 MCDQNNELL 2,582,389

' CARBURETOR SYSTEM Filed Feb. 16, 1949 5 SheetsSheet 3 FiG.7

' Q Q Q l I 10" l i- 7 M 30 ?1'5 18 I 1 L BATTERY TO IGNITION SWITCH v INVENTOR. Randall L.McDonne1l. 7 BY v Aitornegs Patented Jan. 15, 1952 UNITED- STATES PATENT OFFICE 2,582,389 CARBURETOR SYSTEM Randall L. McDonnell, Hattlesburg, Miss.

Application February 16, 1949, Serial No. 76,735 7 Claims. (01. 123-422) This invention relates generally to an improvement in carburetor systems for use with conventional type carburetors installed in automotive, marine and stationary engines and has particular relation to an improved carburetor system and method of carburetion involving the collection of unvaporized fuel in the carburetor, the subsequent vaporization of the collected fuel and its discharge into the carburetor outlet or intake manifold, the device being either in the form of a carburetor system per se or in the form of an attachment for conventional carburetors, particularly those of the down-draft or up-draft type.

Conventional type carburetors discharge fuel from the main discharge nozzle at a small fraction of one pound per square inch pressure and under this low discharge pressure, the fuel is imperfectly vaporized and a large portion thereof remains unvaporized or in large particle, liquid form. Additionally, in the case of carburetors having a throttle valve, the partially vaporized fuel impinges on the cold throttle valve and condensation of the fuel takes place thereon. The net result of supplying unvaporized or imperfectly vaporized fuel to an engine is that part of the fuel is not burned and this unburned portion not only results in a waste of power but also promotes ring sticking, carbon formation, oil dilution, engine wear, etc. Thus, in the case of engines operating on low volatility fuels, such as tractor fuels, these conditions become especially serious.

Numerous devices and methods have been heretofore proposed for improving the efliciency of carburetor systems for engines. Thus, it has been proposed to heat the main fuel discharge nozzle but this system results in condensation of the fuel when it impinges upon the cold throttle valve and mixing chamber of the carburetor. It has also been proposed to provide a heated absorption element adjacent the main fuel discharge nozzle but devices of this type have not proved satisfactory, one reason being that such devices'are not adapted to prevent condensation on the throttle or wall of the mixing chamber. None of the prior art proposals appears to have generally provided an absorption element adjacent the fuel discharge nozzle for collecting unvaporized fuel, transfer means such as a conduit for delivering the unvaporized liquid fuel -to a vaporizer in such manner that the already vaporized fuel will continue through the carburetor system and substantially all of the unvaporized fuel will be co1lected,.transferred to a vaporizer, vaporized and thence injected into the intake manifold passage.

' Accordingly, it is an object of this invention to provide an improved carburetor system, includ ing an improved method of carburetion, which may be in the form of a carburetor system per se, or may be in the form of an attachment for conventional type carburetors so as to provide improved vaporization of the fuel supplied to engines of the type normally using gasoline and other hydrocarbon liquid fuels.

A further object is to provide an improved carburetor system or carburetor attachment which may be used with virtually all engines employing single or multiple barrel carburetors which are generally of the down-draft or up-draft type.

- Another object is to provide an improved carburetor system or vaporizing attachment for a carburetor which will vaporize the unvaporized fuel already in the carburetor system so as to enable the maximum power to be obtained from a given volume of the mixture of air and fuel particles already i the carburetor system.

Another object is to provide an improved carburetor system or vaporizing attachment for a carburetor which will thoroughly vaporize the unvaporized fuel by heating the unvaporized fuel only and will have, at most, a negligible effect on the temperature of the incoming air, so as to enable the maximum power to be obtained from a given volume of the mixture of air and highly vaporized fuel.

A further object of the invention is to provide an improved carburetor system which will utilize the pressure differential which obtains between the air pressure to which the unvaporized fuel collector is subjected (practically atmospheric) and the air pressure to which the vaporizer adjacent the intake manifold is subjected (sub-atmospheric when engine is operating) as an aid in vaporizing the unvaporized fuel present in the carburetor system and also will aid in the self regulation and control of the system generally.

Still another object of the invention is to provide an improved carburetor system which will permit the transfer of unvaporized fuel adjacent the main fuel discharge nozzle zone to the intake manifold zone where the said fuel is vaporized and injected directly into the manifold adjacent one or more of the intake fuel valves in the engine.

Still another object of my invention is to provide an improved carburetor system which is economical to manufacture, which may be selfregulating in operation, which is effective and which may be inexpensively produced in the form of an attachment which may be readily installed in conventional type carburetors.

These and other objects of the invention will be readily understood by reference to the accompanying specification and drawings.

In the conventional automotive engine carburetors, generally only the idling system of the carburetor is supplying fuel to the engine at low speed and/or low power outputs. After a speed of around 20 M. P. H. in high gear has been reached, the main fuel discharge nozzle normally begins to discharge some fuel which is added to the fuel supplied by the idler. As the speed and/or power is increased further, the idling system discharges progressively less fuel and the main fuel discharge nozzle provides progressively more fuel until a speed of around 30 M. P. H. has been reached. At this point the main fuel discharge nozzle normally supplies all of the fuel used by the engine and continues to do so as long as the speed and power are further increased. In other words, the rate of fuel discharged from the main fuel discharge nozzle generally depends upon the rate of acceleration and upon the amount of power required. Thus, the power output of carburetor type engines is roughly proportional to the intake manifold pressure and the greater the amount of power taken from an. engine, the higher will be its manifold pressure, until at wide open throttle the manifold pressure will be practically atmospheric.

In such a carburetor system as shown in the drawings, the present invention generally comprises a vaporizer for the liquid fuel and means, generally including a conduit, adjacent the discharge nozzle for collecting and delivering unvaporized fuel to the vaporizer. The vaporizer is generally in the form of a heated orifice or nozzle, or a heated nozzle. Additionally, the collector element is preferably disposed adjacent the main fuel discharge nozzle and the vaporizer is preferably disposed in or adjacent the intake manifold passage. Thus, in a preferred embodiment, the collector is disposed on the air and fuel inlet side of the throttle and the vaporizer is disposed on the discharge side of the throttle. In one embodiment of the present invention, there is included means responsive to the pressure differential between the area adjacent the collector and the area adjacent the vaporizer for transmitting the liquid fuel'from the collector to the vaporizer and for discharging the resultant fuel from the vaporizer whenever the pressure adjacent the vaporizer is lower than the pressure adjacent the collector. The vaporizer preferably includes heating means to assist in vaporization of the fuel passing therethrough. In a still further embodiment, a vaporizer is disposed in the intake manifold passage adjacent one or more of the engine fuel intake valves so that the vaporized fuel will be distributed directly to the fuel valve intake in order to eliminate condensation and improve evenness of distribution. In a still further embodiment of the invention, a pressure responsive valve or other means is disposed in the conduit or transfer means between the collector and the vaporizer, and alternatively, such pressure responsive valves may be disposed in or form a part of the vaporizer itself.

Referring now to the drawings,

Fig. 1 is a plan view, partially broken away, of a conventional down-draft type carburetor attached to a standard engine intake manifold and incorporating one embodiment of the invention;

Fig. 2 is a top view taken on the line 2-2 of Fig. 1;

Fig. 3 is a cross-sectional view of one form of a portion of a preferred vaporizer of the present invention employing a double poppet valve nozzle arrangement;

Fig. 3a is a cross-sectional view of an embodi ment of the vaporizer of the present invention showing a modified form of valve construction for the nozzle, wherein a single poppet valve is employed;

Fig. 4 is a side view of a modified form of a. fuel collector element forming part of the present invention with the absorption unit broken away in part;

Fig. 4a is a side view of a further modification of the collector unit;

Fig. 5 is a side view, partly broken away, of the top portion of a conventional down-draft carburetor of the Ball and Ball type showing a proposed form of collector unit for use therewith;

Fig. 6 is a top view of the carburetor shown in Fig. 5;

Fig. 7 is a plan view of a conventional automotive engine showing the intake valve, manifold and carburetor, in association with one embodiment of the collector and vaporizer unit of the present invention with a plurality of vaporizer units mounted in the intake manifold adjacent a set of valves, and showing a preferred circuit and switch arrangement for the electric heating coil unit of the Vaporizers, and

Fig. 8 is a side View showing a conventional automotive engine block, intake manifold and carburetor in association with the embodiment of the present invention as shown in Fig. '7 and showing another switch arrangement for the electric heating coil unit of the vaporizer.

Referring now to the drawings, there is shown in Fig. l a carburetor l0 having an air inlet li, a main fuel discharge nozzle l2, an idler valve 13, and a throttle valve M, of the butterfly type. In the conventional down-draft type carburetor shown, the throttle I4 is positioned on the discharge side of the main fuel discharge nozzle l2. The carburetor per se is generally attached by means of a flange I5, carrying screw threaded bolts Hi, to a mating flange I! of an intake manifold l8 leading to the fuel valves as shown in greater detail in Fig. 7.

In the aspect of the invention shown in Fig. l, the collector and vaporizer unit is shown in the form of an attachment for ready installation in a conventional down-draft type carburetor and as such comprises a collector element 2|, a feeding means in the form of a conduit or line 22 and a vaporizer 30. As shown, the collector element 2| is disposed between the main fuel discharge nozzle l2 and the throttle 14. The collector 2i includes an absorbent member comprising a fine mesh metal screen Zia in cylindrical form having an internal cotton layer Zlb, the absorbent member being mounted on a base collecting member comprising a metal saucer or cup Zlc. It will be apparent that alternate types of collectors may be used such as the conical types shown in Figs. 4, 4a, 5 and 6, the latter form preferably having a deposit of cotton or other absorbent material 2 Id in the base.

Various absorbent materials have been found satisfactory for the collector elements Zia, such as absorbent porous ceramics, although the combination of the outer fine mesh metal screen 2 la and the inner-layer of absorbent cotton 21b is generally preferred. However, for all installations, the selection of the material for the collector element will be such as to enable the collector to absorb the maximum quantity of unvaporized fuel flowing from the main fuel discharge nozzle at any given moment within the range of operation of the vaporizer.

As shown, the collector element 2| is connected to the vaporizer 30 as by means of a conduit or line 22 which may be conveniently connected to a borehole 24a in the flange 24 adapted to fit the various styles of conventional carburetors. It will be apparent that this construction is most suitable for use as a carburetor attachment and that in the construction of a new or modified carburetor system it would be most suitable to provide the line 22 by means of a borehole feed (not shown) in the walls of the carburetor chamber.

The vaporizer 30, as shown, is positioned on the discharge side of the throttle l4 and in the opening of the intake manifold i8 with its orifice or spray end 3| directed along the path of the fuel and air coming from the carburetor chamber toward the engine valves. The vaporizer 30 comprises a nozzle 32 which is shown in straight orifice form although a spring loaded poppet valve type such as shown in Figs. 3 and 3a may be used. A fixed valve type, or a needle valve type, or other type valve construction may also be used satisfactorily, depending upon the particular characteristics of the carburetor, the engine and the type of engine operation.

As shown in Fig. 2, the embodiment in the form of an attachment is preferably constructed so that the vaporizer 30 is supported on the attachment flange 24, as by means of radial supports 25, the flange 24 being installed between the carburetor flange l and the intake manifold flange H- with the vaporizer unit 30 directing the vaporized fuel directly into the manifold It as shown in Fig. 1.

As shown, the vaporizer element 30 is suitably mounted in the flange attachment 24, and is pref erably heated, as by means of the electric heating coil circuit 33. Any suitable wiring arrangement to the insulated terminal 33a may be utilized to energize the electric heating coil 33. Preferably the heating circuit is regulated by a vacuum operated switch, the diaphram of which is connected to the intake manifold as shown in Fig. 7. Also, it has been found satisfactory to control the heating coil 33, as by means of a switch operated by linkage to the throttle arm or shaft of the carburetor, as shown in Fig. 8. In order to reduce the drain on the electric power source, which is the storage battery in the case of conventional automotive engines, the switch adjustment in either case is such as to close and energize the nozzle heating circuit when, or shortly after, fuel begins to flow from the main fuel discharge nozzle of the carburetor.

In some installations it is desirable to vary the amount of heat supplied to the vaporizing nozzle and this is readily accomplished by winding tw or more heating coils in parallel on the nozzle and designing the switch so that it is vacuum operated and will cut into the circuit the number of heating coils necessary to thoroughly vapo ize the quantity of fuel flowing through the feed line. It will be understood that a linkage to the throttle valve or shaft could also beused to actuate the switch. As shown in Fig. '7, the wire leading to the vaporizer control switch may be connected to the same side of the ignition switch as is the ignition coil, and this arrangement insures that the vaporizer heating circuit will be open when the engine is not in operation.

Another method of minimizing the amount of electrical current required, which is important in automotive installations, is to preheat the fuel as it passes through the feed line 22. as by means of an enclosing exhaust gas duct or hot water duct (not shown).

In a down-draft carburetor having a main fuel discharge nozzle of the type used in conventional Ball and Ball carburetors, it has been found desirable to construct the collector in the manner shown in Figs. 5 and 6. In this form, the collector element preferably comprises a fine mesh wire screen in the form of an inverted wedgeshaped cone 2 la having two open-faced sides and having a deposit of cotton or other absorbent material 2ld in the base.

Referring now to Figs. 7 and 8 there are shown three vaporizer units 30, each of which is mounted in the intake manifold l8 adjacent a set of two intake valves 40. The vaporizer units 30 are connected by means of an interconnecting feed line 22 to an absorbing and collecting unit in the carburetor Ill. The vaporizing units 33 are heated as shown in Fig. 1 by means of heating coils which are electrically connected by the line 4! to a nozzle switch 42 which is electrically connected, as shown, to the ignition coil terminal of a conventional ignition switch 43 which is in turn electrically connected to a battery or other current source. The nozzle switch 42 is preferably actuated in a conventional manner by a vacuum operated diaphram (not shown), communicating with the intake manifold i 8. In. this manner the nozzle switch 42 may be closed whenever there is a partial vacuum in the intake manifold I3 and will be open whenever the intake manifold is at atmospheric pressure, that is, when the engine is not running. Alternatively, the nozzle switch 44 may be actuated by a conventional linkage arrangement 45 leading to the throttle I4 of the carburetor II), as shown in Fig. 8. In this manner the nozzle switch 44 will be closed whenever the throttle I4 is opened by positive movement 01' the accelerator mechanism. Likewise, the nozzle switch circuit will be open whenever deceleration takes place, or the engine is not running. The

arrangement shown in Figs. 7 and 8 has been found to insure even distribution of the fuel as well as a high degree of fuel vaporization.

In one form of the vaporizer element in which a valve is utilized, as shown in Figs. 3 and 3a, the valve preferably forms a part of the vaporizer nozzle element itself although it will be understood that the valve arrangement may also be installed in the feed line 22. The use of a valve increases the vaporization and generally prevenw the collection and vaporizing system of the present invention from operating as an air bleed when the engine is in operation but the main discharge nozzle i2 is not discharging fuel. If the valve is installed in the feed line 22, it may be pressure responsive, or be actuated by a linkage to the throttle arm or shaft of the carburetor, as by a vacuum diaphragm communicating with the intake manifold in a manner similar to that shown for controlling the nozzle heating element switch 42. Both the valve and the nozzle heating element may be operated by a single vacuum diaphragm, if desired;

In installations where a valve is incorporated as a part of the vaporizer element 30, the constructions shown in Figs. 3 and 3a are preferred. The valvev arrangement preferably includes a rod 50 provided at eitheror both ends with a poppet valve 5!, 52 adapted to be seated in shoulders I3. 54 forming a part of the nozzle passage 32. Preferably, either or both, of the poppet valves II, I!

are held against the pressure in the inlet portion of the feed line 22 by means of a valve spring 55. As long as the manifold pressure M. P. is low; that is, the vacuum is high, atmospheric pressure tends to maintain the upper valve closed against tension of the spring 55 as shown in Fig. 3. When the manifold pressure M. P. rises, as the throttle valve 44 is opened to a predetermined value, the spring 55 tends to unseat the upper valve 5i and tends to partially seat the lower valve 52 under light spring tension. In this embodiment, additional vaporization is gained in that the restricted annular passage between the valves and the valve seats aids in vap'orizing the fuel. As shown in Fig. 3a, the lower poppet valve may be omitted, as is the case when the valve arrangement is incorporated directly in the feed line 22.

In the operation of the present invention, the unvaporized fuel discharged from the main fuel discharge nozzle l2 of the carburetor l0 drips and impinges on the absorption and collector element 2i and is absorbed by the cotton or other absorbent material 2lb or 2Id. That portion of the discharged fuel which is in a vaporized form or does not impinge on the absorption and collection element 2| flows along the annular passage between the collection element 2| and the carburetor wall, past the throttle l4, and toward the intake manifold I 8. The absorbed unvaporized fuel in the absorption member 21b or Zld is forced by gravity and/or atmospheric pressure into the collector member 2|c and thence through the feed line 22 which communicates with the vaporizer element 30, said element being subjected to sub- 1 atmospheric pressure while the engine is operating. It will thus be apparent that a major portion of the unvaporized fuel will be prevented from passing directly in liquid form into the intake manifold. The liquid fuel is vaporized in the vaporizer element 30 by the nozzle passage 32 and/or the heat of vaporization imparted by heating element 33 and is sprayed in vaporized form from the nozzle orifice 3| into the intake manifold passage.

In the case of automobiles operating at normal cruising speed, the manifold pressure M. P. will vary from about to 16 inches of mercury pressure below atmospheric pressure. Since the collector 2| is installed in the carburetor In at a point where the pressure is practically atmospheric and the vaporizer nozzle 30 is installed in or adjacent the intake manifold l8 where the pressure varies from about 10 to 16 inches of mercury below atmospheric pressure, it is evident that the vaporized fuel from the vaporizer nozzle 30 will be discharged at a pressure of approximately 4 to 7 pounds p. s. i. This discharge pressure is many times higher than the pressure at which fuel is discharged from the main discharge nozzle l2 of conventional type carburetors. This higher pressure, especially in conjunction with the heating eflect of the electrically heated nozzle 30 results in discharging the fuel from the vaporizer nozzle 30 in a very highly vaporized state. Further, since the highly vaporized fuel does not come in contact with the cold throttle valve 14, condensation from this source is substantially eliminated.

The main discharge nozzle of an automobile carburetor normally begins to discharge fuel when a speed of 18 to 20 M. P. H. is reached with the car in high gear. Until this discharge begins, the

' vaporizer 30 acts as an air bleed but since the amount of air bled into the carburetor system is 8 small, it has little or no appreciable effect on engine operation either in starting, idling or at idle system speeds. It will be apparent that the present system will not act as an air bleed when the modifications utilizing valve-type nozzles, such as those illustrated in Figs. 3 and 3a, are used.

As set forth above, in the case of both the valveless type of vaporizer shown in Fig. l, and the valve-type vaporizer shown in Figs. 3 and 3a, the point at which the electrical heating element 33 for the vaporizer will be energized is regulated preferably by a vacuum operated switch 42, the diaphragm of which is connected to the intake manifold I 8 as shown in Fig. 7. Alternatively, the nozzle switch 44 can be operated by mechanical linkage to the throttle I4 or shaft of the carburetor [0 as shown in Fig. 8. In either case, the

vacuum operated switch or the linkage arrange-- 'ment may be so adjusted that the vaporizer heating element will be energized whenever or shortly after fuel begins to flow from the main discharge nozzle l2. It will be apparent that the vaporizer element may be heated by a hot water jacket (not shown) connected to the cooling system of the engine or by a hot air jacket or by other conventional heating arrangements in the case of stationary or marine engines. However, electrical heating means have proven most satisfactory.

It will be apparent that the vaporizer element discharges fuel only when the main discharge nozzle of the carburetor is spraying fuel into the carburetor passage. For example, in the case of an automobile engine, at low speeds and/or low power output, only the idle system of the carburetor is supplying fuel to the engine. After a speed of around 20 M. P. H. in high gear is reached, the main fuel discharge nozzle begins to discharge fuel to supplement the fuel supplied by the idle system. As the speed and/or power is increased further, the idle system discharges progressively less fuel and the main discharge nozzle provides progressively more fuel, until a speed of around 30 M. P. H. is reached, at which point the main discharge nozzle commences to supply all of the fuel used by the engine and continues to do so as speed and/or power are further increased.

Thus, the collection and vaporizing system of the present invention collects and vaporizes a major portion of the fuel which is discharged from the main discharge nozzle of the carburetor in an unvaporized state, and transfers such fuel toward the intake manifold where the unvaporized fuel is converted into a highly vaporized form and discharged directly into the manifold. The pressure effective in forcing fuel through the collector and vaporizer system is the difference between atmospheric pressure and pressure obtaining in the intake manifold at any given moment. The effective pressure will be greatest at idling and low power output, and at this stage there will be no fuel discharged from the vaporizer element since the main discharge nozzle of the carburetor will not be emitting fuel.

As an engine approaches wide open throttle, the manifold pressure approaches atmospheric pressure and the effective pressure acting to force fuel through the vaporizer decreases. For use with engines that operate for a considerable portion of the time at or near full throttle, the valvetype .of vaporizer system in which the valve is actuated by linkage to the throttle arm or shaft of the carburetor is very satisfactory. This is true because of the fact that as the throttle is moved to progressively wider open positions and the effective pressure becomes less and less, the restriction offered by the valve to the flow of fuel in the line connecting the collector with the vaporizer element also becomes less. In other words, as the pressure effective in forcing fuel through the vaporizer system becomes less and less, the restriction offered by the valve will also become less and less, thus permitting the required quantity of fuel to flow.

The valveless type vaporizer system is simpler than the above described type and is entirely satisfactory for use in automotive vehicles at cruising speeds and in other types of engines at comparable part-throttle operation.

It will be apparent that in the case of multibarrelled carburetors or in duel carburetor systems, a collector unit should be provided for'each main discharge nozzle. It will also be apparent that the possibility of condensation may be reduced considerably by discharging the highly vaporized fuel from the vaporizer as closely as possible to the intake valves. Moreover, in installations of this type, the intake manifold air temperature may be held to a lower value with an increasingly greater increase in volumetric efliciency.

The improved carburetion system of the present invention provides increased fuel economy and smoother engine operation in addition to reducing engine wear, oil dilution, ring sticking and carbon formation. The improved carburetion system of the present invention may be so constructed as to be self-regulated and positive in action by means of the pressure differentials, thereby eliminating continued care and adjustment. It has been found that maximum advantages of the present invention may be obtained with engines operating on tractor fuels and the like.

It will be apparent that the present invention has been described in its preferred embodiments and that various. modifications may be made which fall within the spirit and scope thereof as set forth in the appended claims.

Iclaim:

l. A carburetor having an air inlet, a discharge nozzle for spraying liquid fuel into the incoming airstream, in combination, means for collecting unvaporized fuel disposed in said air stream adjacent said discharge nozzle and on the down stream side thereof, a vaporizer for said collected unvaporized fuel, and means responsive to the pressure differential between the area adjacent the collecting means and the area adjacent the vaporizer for feeding said unvaporized fuel from said collecting means to said vaporizer and for discharging the resultant vaporized fuel from said vaporizer whenever the pressure adjacent the vaporizer is lower than the pressure adjacent the collecting means.

2. A carburetor having an air inlet, a discharge nozzle for spraying liquid fuel into the incoming air stream; and an intake manifold, in combination, means for collecting unvaporized fuel disposed in said air stream adjacent said discharge nozzle and on the down stream side thereof, a vaporizer disposed in said intake manifold for vaporizing and discharging said collected unvaporized fuel, and means responsive to the pressure differential between the area adjacent the collecting means and the area adjacent the vaporizer for feeding said unvaporized fuel from said collecting means to said vaporizer and for discharging the resultant vaporized fuel from said vaporizer into said intake manifold whenever the pressure in the intake manifold is lower than the pressure adjacent the collecting means.

3. In a carburetor system having an air inlet, a discharge nozzle for spraying liquid fuel into the incoming air stream, and an intake manifold communicating with an engine fuel valve, in combination, means for collecting unvaporized fuel disposed in said air stream adjacent said discharge nozzle and. on the down stream side thereof, a vaporizer for said collected unvaporized fuel disposed in said intake manifold adjacent said engine fuel valve, and means responsive to the pressure differential between the area adjacent the collecting means and the area adjacent the vaporizer for feeding said unvaporized fuel from said collecting means to said vaporizer and for discharging the resultant vaporized fuel from said vaporizer into said intake manifold adjacent said engine fuel valve whenever the pressure in the intake manifold is lower than the pressure adjacent the collecting means.

4. In a carburetor system having an air inlet, a discharge nozzle forspraying liquid fuel into the incoming air stream, in combination, means for collecting unvaporized fuel disposed adjacent said discharge nozzle, a vaporizer for said col-.

lected unvaporized fuel, and means, including a valve, responsive to the pressure differential between the area adjacent the collecting means and the area adjacent the vaporizer for feeding said unvaporized fuel from said collecting means to said vaporizer and for discharging the resultant vaporized fuel from said vaporizer whenever the pressure adjacent the vaporizer is lower than the pressure adjacent the collecting means.

5. In a carburetor system having an air inlet, a discharge nozzle for spraying liquid fuel into the incoming air stream, in combination, means for collecting unvaporized fuel disposed adjacent said discharge nozzle, a vaporizer for said collected unvaporized fuel, and means, including a pressure responsive valve in said vaporizer responsive to the pressure differential between the area adjacent the collecting means and the area adjacent the vaporizer for feeding said unvaporized fuel from said collecting means to said vaporizer and for discharging the resultant vaporized fuel and from said vaporizer whenever the pressure adjacent the vaporizer is lower than the pressure adjacent the collecting means.

6. The combination set forth in claim 1, including means for heating said vaporizer.

7. The combination set forth in claim 1, including means for heating said vaporizer, said heating means being responsive to the pressure differential between the area adjacent the collecting means and the area adjacent the vaporizer.

RANDALL L. MCDONNEIL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name 1 Date 1,017,186 Stewart Feb. 13, 1913 1,618,139 Ryder Feb, 15, 1927 1,802,604 Hofbauer Apr. 28, 1931 1,863,715 Heltger June 21, 1933 1,873,082 Vostrez Aug. 23, 1932 2,175,675 Swengel Oct. 10, 1939 2,333,030 Meyer Oct. 26, 1943 2,426,319 Meyer Feb. 17, 1948 

